700
FXUS65 KGJT 121721
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1121 AM MDT Fri Jul 12 2024

.KEY MESSAGES...

- Near-record daytime temperatures are expected today and
  tomorrow especially in the lower valleys.

- Afternoon showers and thunderstorms will develop over higher
  terrain each day throughout the seven-day forecast with an
  increase in coverage expected early next week.

- Temperatures remain elevated beyond the weekend, but some
  relief is expected from cloud cover and shower activity as
  monsoonal moisture is forecast to return early next week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 313 AM MDT Fri Jul 12 2024

The forecast remains on track for near-record daytime temperatures
today and tomorrow as a high pressure center continues to move in
overhead. As a result, a Heat Advisory is in effect for the lower
valleys of eastern Utah and the Grand Valley in western Colorado
beginning this morning at 10 AM. Limit exposure to the elements when
possible.

This morning`s water vapor satellite imagery continues to
show a seasonably dry airmass in place across the forecast area, but
you can also see moisture beginning to wrap itself around the high
pressure system into parts of western and central Utah. We`ll have
to wait a few more days until it advects into our neck of the woods,
but in the meantime isolated afternoon showers and storms will
continue to form over the southern mountains. This is where CAPE and
moisture availability is favored today and tomorrow. The primary
threats from any storms that develop are lightning and gusty
outflows up to 50 mph.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 313 AM MDT Fri Jul 12 2024

On Sunday the high pressure becomes centered over central CO. This
position will allow for monsoon moisture that has been rotating
clockwise around the high to reach our area. This will result in a
increase in coverage of showers and thunderstorms. The best coverage
will be over the higher terrain. Given the proximity to the high our
temperatures will still be quite warm leaving lower valleys with
modest dew point spreads. This in turn will limit measurable
rainfall and promote gusty winds. Although this increased coverage
may bring some relief to the afternoon heat through clouds and cool
outflows. PWAT values reach 100-150 percent of normal for most
locations and the 700 mb mixing ratios peak at around 5 g/kg. This
moisture is not the highest of quality therefore the potential for
heavy rainfall is marginal for now. The mositure does not change
much on Monday so expect scattered to widespread afternoon showers
and storms once again. The high will then meander in a westward
direction as a low pressure system tracks over the Northern Plains.
Usually when that happens there is a disruption to the monsoon
moisture, which can change storm coverage and intensity. The details
from Tuesday onward are not clear at this point. Temperatures still
look to remain above normal heading into next week, but not quite as
hot as today and tomorrow.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1118 AM MDT Fri Jul 12 2024

Under high pressure, look for generally clear skies this
afternoon and evening. A few storms are possible in and around
the San Juans, so have included VCTS for KTEX, KDRO, and KGUC.
Winds will be northerly and gust up to around 20 knots this
afternoon, before dropping and once again becoming light and
terrain driven. VFR conditions will prevail. Main threats with
any passing shower or storm will be gusty outflow winds and
lightning. Construction near the runway at KGJT has led to
periods of reduced visibility, so have included a tempo group to
account for this.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Heat Advisory until 9 PM MDT Saturday for COZ006.
UT...Heat Advisory until 9 PM MDT Saturday for UTZ024-027-029.

&&

$$

SHORT TERM...KAA
LONG TERM...KJS
AVIATION...TGJT